Polypropylene composite material and preparation method thereof

Abstract

The invention provides a polypropylene composite material and a preparation method thereof. The polypropylene composite material is prepared from the following components in parts by weight: 68 to 89 parts of a polypropylene composite matrix, 12 to 29 parts of carbon fibers, 0.1 to 1.5 parts of fullerene, 2.0 to 6.3 parts of polypropylene grafted maleic anhydride and 0.05 to 0.6 part of an antioxidant. The polypropylene composite material provided by the invention has the characteristics of high strength, high toughness, high wear resistance and long-acting stability, and can meet the urgent demand of high-end industrial equipment on light-weight and long-life materials.

Description

Technical Field

[0001] This disclosure relates to the field of composite materials technology, and in particular to a polypropylene composite material and a method for preparing the same. Background Technology

[0002] Polypropylene, as one of the most widely produced general-purpose plastics, is widely used in the automotive, electronics, and packaging industries due to its excellent chemical stability, ease of processing, and low cost. However, its low strength and modulus, poor wear resistance, and weak aging resistance severely limit its application in high-end industrial scenarios. With the explosive growth in demand for lightweight and long-life materials in fields such as new energy vehicles and aerospace, the development of high-performance polypropylene-based composite materials has become an urgent need for the industry. Summary of the Invention

[0003] To address the problems existing in related technologies, this disclosure provides a polypropylene composite material and a method for preparing the same.

[0004] According to a first aspect of the present disclosure, a polypropylene composite material is provided, the composite material comprising the following components, the content of each component being expressed by weight as follows: 68-89 parts of polypropylene composite matrix 12-29 parts carbon fiber 0.1 to 1.5 parts of fullerene, Polypropylene grafted with maleic anhydride, 2.0~6.3 parts, Antioxidant 0.05~0.6 parts.

[0005] In some embodiments of this disclosure, the ratio C1 = m1 / (m2+m3) of the sum of the weight m1 of the polypropylene composite matrix, the weight m2 of the carbon fiber, and the weight m3 of the fullerene is (2.5~7.1):1.

[0006] In some embodiments of this disclosure, the ratio of the weight m2 of the carbon fiber to the weight m3 of the fullerene, C2 = m2 / m3, is (20.4~158.3):1.

[0007] In some embodiments of this disclosure, the ratio of the sum of the weights of the polypropylene composite matrix (m1), the carbon fiber (m2), and the fullerene (m3) to the sum of the weights of the polypropylene grafted with maleic anhydride (m4) and the antioxidant (m5) is C3 = (m1 + m2 + m3) / (m4 + m5) (15.7~52.6):1.

[0008] In some embodiments of this disclosure, the length of the carbon fiber is 1~2 mm; The carbon fiber includes T700 grade short-cut carbon fiber and T800 grade short-cut carbon fiber, and the weight ratio of the T700 grade short-cut carbon fiber to the T800 grade short-cut carbon fiber is (0.5~1.5):1.

[0009] In some embodiments of this disclosure, the grafting content of maleic anhydride in the polypropylene grafted with maleic anhydride is 0.4% to 1.5%.

[0010] In some embodiments of this disclosure, the fullerene includes C 60 C 70 C 76 C 80 At least one of them; The antioxidants include hindered phenolic antioxidants.

[0011] In some embodiments of this disclosure, the polypropylene composite matrix comprises homopolymer polypropylene and block copolymer polypropylene, wherein the weight ratio of the homopolymer polypropylene to the block copolymer polypropylene is (1.4~2.6):1.

[0012] According to a second aspect of the present disclosure, a method for preparing a polypropylene composite material is provided, the method being used to prepare the aforementioned polypropylene composite material; the method includes: Polypropylene composite matrix, polypropylene grafted maleic anhydride and antioxidant are melt-blended and extruded and granulated under a first preset condition to obtain modified polypropylene particles. The modified polypropylene particles, carbon fibers, and fullerenes are melt-blended and extruded and granulated under a second preset condition to obtain the polypropylene composite material.

[0013] In some embodiments of this disclosure, the preparation method further includes, prior to the melt blending of the modified polypropylene particles, carbon fibers, and fullerenes: The carbon fibers and fullerenes were modified using a composite coupling agent to obtain modified carbon fibers and modified fullerenes, respectively. The mass fraction of the solute in the composite coupling agent is 0.2%~1.0%; the composite coupling agent includes γ-aminopropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane, and the weight ratio of γ-aminopropyltriethoxysilane to γ-glycidoxypropyltrimethoxysilane is (0.5~1.5):1.

[0014] The beneficial effects of this disclosure include, but are not limited to: the polypropylene composite material provided by this disclosure has the characteristics of high strength, high toughness, high wear resistance, and long-term stability, which can meet the urgent needs of high-end industrial equipment for lightweight and long-life materials.

[0015] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and are not intended to limit this disclosure. Attached Figure Description

[0016] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the present disclosure and, together with the description, serve to explain the principles of these embodiments. In these drawings, similar reference numerals are used to denote similar elements. The drawings described below are some embodiments of the present disclosure, but not all embodiments. Other drawings will be readily available to those skilled in the art based on these drawings without inventive effort.

[0017] Figure 1 This is a schematic flowchart of a method for preparing a polypropylene composite material according to an exemplary embodiment of the present disclosure. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this disclosure clearer, the technical solutions of this disclosure will be clearly and completely described below in conjunction with the embodiments of this disclosure. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. Based on the embodiments in this disclosure, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this disclosure. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of this disclosure can be arbitrarily combined with each other.

[0019] This disclosure provides a polypropylene composite material, which includes the following components, the contents of which are expressed by weight as follows: 68-89 parts of polypropylene composite matrix, 12-29 parts of carbon fiber, 0.1-1.5 parts of fullerene, 2.0-6.3 parts of polypropylene grafted maleic anhydride, and 0.05-0.6 parts of antioxidant.

[0020] In the polypropylene composite material provided in this embodiment, the polypropylene composite matrix serves as the matrix of the polypropylene composite material, ensuring the basic processability and mechanical properties of the polypropylene composite material. Carbon fiber, as the reinforcing phase of the polypropylene composite matrix, can improve the lightweight and mechanical properties of the polypropylene composite material.

[0021] Fullerenes, such as C 60Fullerenes, being spherical molecules, are dispersed as fillers in polypropylene composites. Their spherical structure ensures uniform stress distribution under stress from all directions, preventing stress concentration. Furthermore, these rigid spherical molecules dispersed within the polypropylene composite can rotate or roll freely or semi-freely. When the polypropylene composite is subjected to friction, the fullerene spherical molecules act like "nano-balls," converting sliding friction into rolling friction, thereby improving the wear resistance of the polypropylene composite. Secondly, the spherical surface of the fullerene molecule is a highly delocalized conjugated π-electron system. When friction occurs in the fullerene composite, this delocalized π-electron system can absorb and dissipate the mechanical energy generated during friction. This prevents the mechanical energy from being entirely used to break the chemical bonds of the molecules in the polypropylene composite, thus reducing wear on the polypropylene composite material. Furthermore, the nanoscale diameter of fullerenes induces a quantum confinement effect in their electronic energy levels. This allows for transient changes in their electronic states under extreme frictional conditions. For example, they may buffer impacts through instantaneous electron cloud deformation or promote the formation of a transfer film with superior lubrication properties at the friction interface, thereby enhancing the wear resistance of polypropylene composites. Therefore, fullerenes can enhance the wear resistance of polypropylene composites by leveraging the combined characteristics of "spherical molecules + electronic structure + quantum effects."

[0022] Maleic anhydride grafted onto polypropylene serves as a compatibilizer. Its anhydride groups can react with the polar groups on the surface of carbon fibers and fullerenes, while its polypropylene segments are compatible with the polypropylene composite matrix. This creates a connecting bridge between the carbon fibers, fullerenes, and the polypropylene composite matrix, improving interfacial adhesion and preventing failure of the polypropylene composite material due to stress concentration when subjected to friction or impact.

[0023] Antioxidants in polypropylene composites can effectively inhibit the degradation and aging of the polypropylene composite matrix during processing and use, maintain the integrity of the molecular chains of the polypropylene composite matrix, and thus ensure the stability of the performance and service life of the polypropylene composite.

[0024] In polypropylene composites, 68-89 parts by weight of the polypropylene matrix ensure good processability and basic toughness. 12-29 parts by weight of carbon fiber significantly enhances the strength of the polypropylene composite while avoiding processing difficulties and increased brittleness due to excessive content. Considering the high cost and extremely high specific surface area of ​​fullerenes, excessive addition can easily lead to agglomeration; 0.1-1.5 parts by weight of fullerene can significantly improve the wear resistance of the polypropylene composite. 2.0-6.3 parts by weight of polypropylene-grafted maleic anhydride can effectively coat carbon fibers and fullerenes within the polypropylene composite, thereby improving the interfacial properties between the polypropylene matrix and the carbon fibers and fullerenes. 0.05-0.6 parts by weight of antioxidant can inhibit the degradation and aging of the polypropylene matrix during processing and use. Therefore, the polypropylene composite provided in this embodiment possesses high strength, high toughness, high wear resistance, and long-term stability, meeting the urgent needs of high-end industrial equipment for lightweight, long-life materials.

[0025] In one embodiment, the ratio of the weight m1 of the polypropylene composite matrix to the sum of the weight m2 of the carbon fiber and the weight m3 of the fullerene, C1 = m1 / (m2+m3), is (2.5~7.1):1.

[0026] The ratio C1, which is the sum of the weights of the polypropylene matrix (m1), carbon fiber (m2), and fullerene (m3), represents the weight ratio of the "matrix phase" to the "reinforcing phase" in the polypropylene composite. When C1 is within the range of (2.5~7.1):1, it balances the processing fluidity and reinforcing effect of the polypropylene composite. When C1 is below this range (2.5~7.1):1, meaning the "matrix phase" content is too low and the "reinforcing phase" content is too high, the polypropylene composite will have poor melt flowability during preparation, making it difficult to process, and the composite will be too rigid and brittle. When C1 is above this range (2.5~7.1):1, meaning the "matrix phase" content is too high and the "reinforcing phase" content is too low, the reinforcing effect of the "reinforcing phase" on the polypropylene composite is not significant, making it difficult to guarantee the strength of the polypropylene composite. The ratio C1 of the weight m1 of the polypropylene composite matrix to the sum of the weight m2 of the carbon fiber and the weight m3 of the fullerene can be, for example, 2.5:1, 3.6:1, 4.9:1, 6.2:1 or 7.1:1. The ratio C1 of the weight m1 of the polypropylene composite matrix to the sum of the weight m2 of the carbon fiber and the weight m3 of the fullerene can also be any value between the exemplary ratios. For example, the ratio C1 of the weight m1 of the polypropylene composite matrix to the sum of the weight m2 of the carbon fiber and the weight m3 of the fullerene can be any value between (3.6~6.2:1).

[0027] In one embodiment, the ratio of the weight m2 of carbon fiber to the weight m3 of fullerene, C2 = m2 / m3, is (20.4~158.3):1.

[0028] Carbon fibers and fullerenes are reinforcing fillers in polypropylene composites. Carbon fibers, with their high aspect ratio, interweave to form a robust three-dimensional network skeleton, providing a smooth bearing surface when the polypropylene composite is subjected to loads, especially mechanical forces during friction. Fullerenes, on the other hand, fill microscopic defects in the polypropylene matrix. These fullerene spherical molecules can rotate or roll freely or semi-freely. When the polypropylene composite is subjected to friction, these fullerene spherical molecules act like "nanoballs," transforming sliding friction into rolling friction. Furthermore, they can form a transfer film with superior lubrication properties at the friction interface, thereby improving the wear resistance of the polypropylene composite. Therefore, through the dual action mechanism of carbon fibers and fullerenes, when the polypropylene composite is subjected to friction, it can provide a smooth bearing surface while forming a dual lubrication layer of "nanoballs + transfer film" at the friction interface, thus improving the wear resistance of the polypropylene composite.

[0029] When the ratio of carbon fiber weight (m2) to fullerene weight (m3), C2 = m2 / m3, is higher than (20.4~158.3):1, meaning the carbon fiber content is high while the fullerene content is low, it is insufficient to effectively enhance the wear resistance of polypropylene composites. Conversely, when the ratio of carbon fiber weight (m2) to fullerene weight (m3), C2 = m2 / m3, is lower than (20.4~158.3):1, meaning the carbon fiber content is low while the fullerene content is high, fullerene is prone to agglomeration in polypropylene composites, causing defects and increasing costs. For example, the ratio C2 = m2 / m3 of the weight of carbon fiber m2 to the weight of fullerene m3 can be 20.4:1, 46.3:1, 75.1:1, 100.5:1 or 158.3:1. The ratio C2 = m2 / m3 of the weight of carbon fiber m2 to the weight of fullerene m3 can also be any value between the exemplary ratios, such as any value in (46.3~100.5):1.

[0030] In one embodiment, the ratio of the sum of the weights of the polypropylene composite matrix (m1), carbon fiber (m2), and fullerene (m3) to the sum of the weights of the polypropylene grafted maleic anhydride (m4) and antioxidant (m5) is C3 = (m1 + m2 + m3) / (m4 + m5) (15.7~52.6):1.

[0031] Polypropylene composite matrix, carbon fiber, and fullerene are the main components of polypropylene composite materials. Polypropylene grafted maleic anhydride and antioxidants are the functional additives. Therefore, the ratio C3 of the sum of the weights of the polypropylene composite matrix (m1), carbon fiber (m2), and fullerene (m3) to the sum of the weights of the polypropylene grafted maleic anhydride (m4) and antioxidants (m5) represents the proportional relationship between the main components and functional additives in the polypropylene composite material. When the ratio C3 of the sum of the weights of the polypropylene composite matrix (m1), carbon fiber (m2), and fullerene (m3) to the sum of the weights of the polypropylene grafted maleic anhydride (m4) and antioxidants (m5) is lower than (15.7~52.6):1, indicating a low proportion of main components and a high proportion of functional additives in the polypropylene composite material, it leads to a waste of functional additives and does not benefit the performance of the polypropylene composite material. When the ratio C3 of the sum of the weights of the polypropylene composite matrix (m1), carbon fiber (m2), and fullerene (m3) to the sum of the weights of the polypropylene grafted maleic anhydride (m4) and antioxidant (m5) is higher than (15.7~52.6):1, that is, when the main components in the polypropylene composite material are more numerous and the functional additives are fewer, the interface modification and antioxidant effects are insufficient. For example, the ratio C3 of the sum of the weights of the polypropylene composite matrix (m1), carbon fiber (m2), and fullerene (m3) to the sum of the weights of the polypropylene grafted maleic anhydride (m4) and antioxidant (m5) can be 15.7:1, 25.6:1, 32.4:1, 45.3:1, or 52.6:1. The ratio C3 can also be any value between the exemplary ratios. For example, the ratio C3 of the sum of the weights of the polypropylene composite matrix (m1), carbon fiber (m2), and fullerene (m3) to the sum of the weights of the polypropylene grafted maleic anhydride (m4) and antioxidant (m5) can be any value between (25.6~45.3):1.

[0032] In one embodiment, the length of the carbon fiber is 1~2mm. The carbon fiber includes T700 grade chopped carbon fiber and T800 grade chopped carbon fiber, and the weight ratio of T700 grade chopped carbon fiber to T800 grade chopped carbon fiber is (0.5~1.5):1.

[0033] In this embodiment, short-cut carbon fibers with a length of 1-2 mm are used to balance the dispersion and reinforcing effect of carbon fibers in the polypropylene composite matrix. Carbon fibers that are too short have limited reinforcing effect on the polypropylene composite matrix, while carbon fibers that are too long are difficult to disperse and prone to clumping. For example, the length of the carbon fibers can be 1 mm, 1.5 mm, or 2 mm, or any value between these exemplary lengths, such as 1.2-1.8 mm.

[0034] The T700 and T800 grade chopped carbon fibers used in this embodiment have monofilament diameters of 7 mm and 5 mm, respectively. The bi-stage blending of these two fibers utilizes their diameter difference to construct a "coarse-fine" interlocking carbon fiber network. While the T700 grade chopped carbon fibers provide structural strength, the T800 grade fibers exhibit high modulus to suppress shear deformation, thereby enhancing the mechanical properties of the polypropylene composite. A weight ratio of T700 to T800 grade chopped carbon fibers within the range of (0.5~1.5):1 balances the strength, modulus, and toughness of the polypropylene composite. For example, the weight ratio of T700 grade chopped carbon fiber to T800 grade chopped carbon fiber can be 0.5:1, 1:1 or 1.5:1. The weight ratio of T700 grade chopped carbon fiber to T800 grade chopped carbon fiber can also be any value between the exemplary ratios, such as any value between (0.8~1.2):1.

[0035] In one embodiment, the grafting content of maleic anhydride in the polypropylene grafted with maleic anhydride is 0.4% to 1.5%.

[0036] Polypropylene grafted with maleic anhydride can be, for example, at least one of polypropylene grafted with maleic anhydride 1010, polypropylene grafted with maleic anhydride 1020, and polypropylene grafted with maleic anhydride 1030. The grafting content of maleic anhydride in polypropylene grafted with maleic anhydride is in the range of 0.4% to 1.5%, ensuring that the grafted maleic anhydride acts as a compatibilizer with sufficiently high reactivity without causing significant negative degradation to the polypropylene composite matrix. When the grafting content of maleic anhydride in polypropylene grafted with maleic anhydride is below 0.4% to 1.5%, the grafting rate is too low, resulting in insufficient active sites on the molecular chain for reaction with carbon fibers and fullerene fillers, leading to poor interfacial modification. When the grafting content of maleic anhydride in polypropylene grafted with maleic anhydride is above 0.4% to 1.5%, the grafting rate is too high, which may lead to excessive reaction, causing degradation of the polypropylene composite matrix backbone, a decrease in molecular weight, and ultimately damage to the mechanical properties of the polypropylene composite matrix itself. For example, the grafting content of maleic anhydride in polypropylene grafted with maleic anhydride can be 0.4%, 0.6%, 0.8%, 1.2%, or 1.5%. The grafting content of maleic anhydride in polypropylene grafted with maleic anhydride can also be any value between the exemplary contents, such as any value between 0.6% and 1.2%.

[0037] In one embodiment, the fullerene includes C 60 C 70 C 76 C 80 At least one of them.

[0038] In this embodiment, C is selected. 60 C 70 C 76 C 80 Fullerenes are molecules with moderate size and relatively high stability, and they are commercially available and readily available.

[0039] In one embodiment, the antioxidant includes a hindered phenolic antioxidant. For example, the antioxidant may be at least one of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, and 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)isocyanuric acid.

[0040] Hindered phenolic antioxidants can effectively interrupt the oxidative degradation chain reaction of polypropylene composite matrix by capturing free radicals. They have good compatibility with polypropylene composite matrix and are not easily precipitated, thus providing long-term thermo-oxidative stability protection.

[0041] In one embodiment, the polypropylene composite matrix includes homopolymer polypropylene and block copolymer polypropylene, wherein the weight ratio of homopolymer polypropylene to block copolymer polypropylene is (1.4~2.6):1.

[0042] Homopolymer polypropylene has high molecular chain regularity and high crystallinity, resulting in better rigidity, strength, and heat resistance. Block copolymer polypropylene introduces a rubber phase, which can significantly improve the material's impact toughness and low-temperature performance. In this embodiment, a composite matrix of homopolymer polypropylene and copolymer polypropylene is used, and the weight ratio of homopolymer polypropylene to block copolymer polypropylene is controlled at (1.4~2.6):1. This ensures rigidity while providing toughening with a rubber phase, and the presence of copolymer polypropylene provides sufficient space for fullerene preferential dispersion, preventing its agglomeration in the rigid phase. For example, the weight ratio of homopolymer polypropylene to block copolymer polypropylene can be 1.4:1, 1.8:1, 2.3:1, or 2.6:1, and the weight ratio of homopolymer polypropylene to block copolymer polypropylene can also be any value between the exemplary ratios, such as any value between (1.6~2.4):1.

[0043] This disclosure provides a method for preparing a polypropylene composite material, which is used to prepare the aforementioned polypropylene composite material. For example... Figure 1 As shown, the preparation method includes: S100. Polypropylene composite matrix, polypropylene grafted maleic anhydride and antioxidant are melt-blended and extruded and granulated under the first preset conditions to obtain modified polypropylene particles.

[0044] Before preparation begins, the polypropylene composite matrix, carbon fiber, fullerene, polypropylene grafted maleic anhydride, and antioxidant raw materials can be placed in a vacuum drying oven at 75~85℃ for 10~15 hours to dry and then taken out for use.

[0045] The polypropylene composite matrix and polypropylene grafted maleic anhydride are weighed separately according to the above-mentioned weight proportions, and mixed in a mixer at a speed of 500-700 r / min and a temperature of 90-100°C for 8-15 minutes. The mixing speed can be, for example, 500 r / min, 600 r / min, or 700 r / min, or any value between these exemplary speeds, such as any value between 550-650 r / min. The mixing temperature can be, for example, 90°C, 95°C, or 100°C, or any value between these exemplary temperatures, such as any value between 92-96°C. The mixing time can be, for example, 8 minutes, 10 minutes, or 15 minutes, or any value between these exemplary times, such as any value between 9-12 minutes.

[0046] According to the above-mentioned weight proportions, an antioxidant is added to the polypropylene composite matrix and the polypropylene grafted maleic anhydride mixture, and the mixture is blended for 8 to 15 minutes in a high-speed mixer at 500-700 r / min and 70-90°C. The blending speed can be, for example, 500 r / min, 600 r / min, or 700 r / min, or any value between these exemplary speeds, such as any value between 550 and 650 r / min. The blending temperature can be, for example, 70°C, 80°C, or 90°C, or any value between these exemplary temperatures, such as any value between 72 and 86°C. The blending time can be, for example, 8 minutes, 10 minutes, or 15 minutes, or any value between these exemplary times, such as any value between 9 and 12 minutes.

[0047] The mixture is then fed into a twin-screw extruder for melt blending, extruded and granulated under a first preset condition, and then cooled and dried to obtain modified polypropylene particles. The first preset condition is as follows: the temperatures of zones one through four of the twin-screw extruder are set to 70-90℃, 110-130℃, 150-170℃, 210-230℃, and 175-230℃, respectively; the main extruder speed is 25-35 r / min; and the feed speed is 10-20 r / min. The main extruder speed can be, for example, 25 r / min, 30 r / min, or 35 r / min, or any value within the exemplary range, such as any value between 28 and 32 r / min. The feed speed can be, for example, 10 r / min, 15 r / min, or 20 r / min, or any value within the exemplary range, such as any value between 12 and 18 r / min.

[0048] S200: Modified polypropylene particles, carbon fibers and fullerenes are melt-blended and extruded and granulated under a second preset condition to obtain a polypropylene composite material.

[0049] Modified polypropylene particles, carbon fibers, and fullerenes are blended in a high-speed mixer at a speed of 300-400 r / min and a temperature of 70-90°C to obtain a pre-blended material. The blending speed can be, for example, 300 r / min, 350 r / min, or 400 r / min, or any value within the exemplary range, such as any value between 320 and 380 r / min. The blending temperature can be, for example, 70°C, 80°C, or 90°C, or any value within the exemplary range, such as any value between 72 and 86°C.

[0050] The pre-blended material is added to a twin-screw extruder for melt blending, and then extruded and granulated under second preset conditions. After cooling and drying, a polypropylene composite material is obtained. The second preset conditions are: the temperatures of zones one through four of the twin-screw extruder are set to 70-90℃, 110-130℃, 150-170℃, 210-230℃, and 175-230℃, respectively; the main extruder speed is 15-25 r / min; and the feed speed is 10-20 r / min. The main extruder speed can be, for example, 15 r / min, 20 r / min, or 25 r / min, or any value within the exemplary range, such as 18-22 r / min. The feed speed can be, for example, 10 r / min, 15 r / min, or 20 r / min, or any value within the exemplary range, such as 12-18 r / min.

[0051] In this embodiment, in step S100, the polypropylene composite matrix, polypropylene grafted maleic anhydride, and antioxidant are first melt-blended and granulated to prepare modified polypropylene particles, ensuring that the polypropylene grafted maleic anhydride compatibilizer and antioxidant are uniformly pre-dispersed in the polypropylene composite matrix. In step S200, the addition of carbon fibers and fullerenes can shorten their residence time in the high-temperature, high-shear melt, thereby minimizing damage to the length of the carbon fibers and reducing the risk of agglomeration or structural damage to fullerenes due to prolonged shear heating. This helps retain the inherent properties of carbon fibers and fullerenes and promotes their uniform dispersion in the polypropylene composite matrix.

[0052] In one embodiment, before melt-blending the modified polypropylene particles, carbon fibers, and fullerenes, the preparation method further includes: modifying the carbon fibers and fullerenes with a composite coupling agent to obtain modified carbon fibers and modified fullerenes, respectively.

[0053] The composite coupling agent is diluted with anhydrous ethanol and stirred at 50-70°C for 8-15 minutes using a magnetic stirrer to obtain a composite coupling agent solution. The stirring temperature can be, for example, 50°C, 60°C, or 70°C, or any value between these exemplary temperatures, such as any value between 55-65°C. The stirring time can be, for example, 8 minutes, 10 minutes, or 15 minutes, or any value between these exemplary times, such as any value between 10-12 minutes.

[0054] Subsequently, the carbon fibers and fullerenes were immersed in a composite coupling agent solution for 1-3 hours, then removed and dried in a vacuum drying oven at 110-130℃ for 5-7 hours to obtain modified carbon fibers and modified fullerenes. The immersion time can be, for example, 1 hour, 2 hours, or 3 hours, or any value between these examples, such as 1.5-2.5 hours. The drying temperature can be, for example, 110℃, 120℃, or 130℃, or any value between these examples, such as 115-125℃. The drying time can be, for example, 5 hours, 6 hours, or 7 hours, or any value between these examples, such as 5.5-6.5 hours.

[0055] Before blending, carbon fibers and fullerenes are pretreated with a composite coupling agent. One end of the composite coupling agent can react with hydroxyl groups and other groups on the surface of carbon fibers and fullerene fillers, while the other end can interact or react with the polypropylene composite matrix or polypropylene grafted maleic anhydride compatibilizer, thereby further improving the interfacial bonding strength and strengthening the interfacial bond.

[0056] In one embodiment, the mass fraction of the solute in the composite coupling agent is 0.2% to 1.0%; the composite coupling agent includes γ-aminopropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane, and the weight ratio of γ-aminopropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane is (0.5 to 1.5): 1.

[0057] In this embodiment, a composite coupling agent of γ-aminopropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane with a weight ratio of (0.5~1.5):1 is used to achieve functional complementarity. For example, the weight ratio of γ-aminopropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane can be 0.5:1, 1:1, or 1.5):1, and the weight ratio can also be any value between the exemplary weight ratios, such as any value between (0.8~1.2):1. Aminosilanes have high reactivity, while epoxysilanes form a more flexible interfacial layer. The combination of the two can produce a synergistic effect, constructing a stronger and more durable interfacial bonding layer. Using a composite coupling agent with a solute mass fraction of 0.2% to 1.0% is sufficient to form an effective coating on the surface of carbon fibers and fullerene fillers. Excessive use is not only wasteful but may also lead to interfacial defects due to multilayer adsorption. For example, the solute mass fraction of the composite coupling agent can be 0.2%, 0.5%, 0.8%, or 1.0%, or any value within the exemplary mass fraction range, such as any value between 0.4% and 0.8%.

[0058] To more clearly explain the technical solutions provided by the exemplary embodiments of this disclosure, a specific example of the preparation method of the polypropylene composite material provided by the exemplary embodiments of this disclosure is given.

[0059] The polypropylene composite matrix, carbon fiber, fullerene, polypropylene grafted maleic anhydride, and antioxidant raw materials were placed in a vacuum drying oven at 80℃ for 12 hours to dry and then taken out for use.

[0060] The polypropylene composite matrix and the polypropylene grafted maleic anhydride were weighed according to the above weight proportions, and then mixed in a mixer at a speed of 600 r / min and a temperature of 95℃ for 10 min.

[0061] Antioxidants were added to the above-mentioned polypropylene composite matrix and polypropylene grafted maleic anhydride mixture, and the mixture was blended for 10 minutes in a high-speed mixer at 600 r / min and 80℃. The resulting product was then fed into a twin-screw extruder for melt blending, extrusion granulation, and cooling and drying to obtain modified polypropylene particles. The temperatures of zones one through four of the twin-screw extruder were set to 80℃, 120℃, 160℃, 220℃, and 175~230℃, respectively; the main extruder speed was 30 r / min; and the feed speed was 15 r / min.

[0062] The composite coupling agent was diluted with anhydrous ethanol and stirred at 60°C for 10 min using a magnetic stirrer to obtain a composite coupling agent solution. Subsequently, the chopped carbon fibers and fullerenes were placed in the composite coupling agent solution for 2 h, and then removed and dried in a vacuum drying oven at 120°C for 6 h to obtain modified carbon fibers and modified fullerenes.

[0063] Modified polypropylene particles, modified carbon fibers, and modified fullerenes are placed in a high-speed mixer at a speed of 350 r / min and a temperature of 80°C for blending to obtain a pre-blended material.

[0064] The pre-blended material is added to a twin-screw extruder for melt blending, extrusion granulation, and then cooled and dried to obtain a polypropylene composite material. The temperatures of zones one through four of the twin-screw extruder are set to 80℃, 120℃, 160℃, 220℃, and 175~230℃, respectively; the main extruder speed is 20 r / min; and the feeding speed is 15 r / min.

[0065] Following the preparation methods described in the specific examples above, the weight proportions of each component were adjusted to prepare polypropylene composite particles as in Examples 1-13 and Comparative Example 1. The polypropylene composite particles from Examples 1-13 and Comparative Example 1 were subjected to tensile, notched impact, and flexural property tests according to ASTM D638, GB / T 1043-2008, and GB / T 9341-2008, and wear rate tests were also performed. Details are shown in Table 1. Table 1

[0066] Table 1 (continued)

[0067] As can be seen from Table 1, the polypropylene composite material prepared by the exemplary embodiment of this disclosure, and by controlling the amount of each component within an appropriate range, has good mechanical properties and wear resistance.

[0068] The above-described contents can be implemented individually or in various combinations, and all such variations are within the scope of this disclosure.

[0069] Finally, it should be noted that in this document, the terms “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0070] The above embodiments are only used to illustrate the technical solutions of this disclosure, and are not intended to limit it. Although this disclosure has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this disclosure.

Claims

1. A polypropylene composite material, characterized in that, The composite material comprises the following components, the content of which is expressed by weight as follows: 68-89 parts of polypropylene composite matrix 12-29 parts carbon fiber 0.1 to 1.5 parts of fullerene, Polypropylene grafted with maleic anhydride, 2.0~6.3 parts, Antioxidant 0.05~0.6 parts.

2. The polypropylene composite material according to claim 1, characterized in that, The ratio C1 = m1 / (m2+m3) of the sum of the weights of the polypropylene composite matrix m1, carbon fiber m2, and fullerene m3 is (2.5~7.1):

1.

3. The polypropylene composite material according to claim 1, characterized in that, The ratio of the weight m2 of the carbon fiber to the weight m3 of the fullerene, C2 = m2 / m3, is (20.4~158.3):

1.

4. The polypropylene composite material according to claim 1, characterized in that, The ratio of the sum of the weights of the polypropylene composite matrix (m1), the carbon fiber (m2), and the fullerene (m3) to the sum of the weights of the polypropylene grafted with maleic anhydride (m4) and the antioxidant (m5) is C3 = (m1 + m2 + m3) / (m4 + m5) (15.7~52.6):

1.

5. The polypropylene composite material according to any one of claims 1 to 4, characterized in that, The length of the carbon fiber is 1~2mm; The carbon fiber includes T700 grade short-cut carbon fiber and T800 grade short-cut carbon fiber, and the weight ratio of the T700 grade short-cut carbon fiber to the T800 grade short-cut carbon fiber is (0.5~1.5):

1.

6. The polypropylene composite material according to claim 1, characterized in that, The grafting content of maleic anhydride in the polypropylene grafted with maleic anhydride is 0.4% to 1.5%.

7. The polypropylene composite material according to claim 1, characterized in that, The fullerene includes C 60 C 70 C 76 C 80 At least one of them; The antioxidants include hindered phenolic antioxidants.

8. The polypropylene composite material according to claim 1, characterized in that, The polypropylene composite matrix comprises homopolymer polypropylene and block copolymer polypropylene, wherein the weight ratio of the homopolymer polypropylene to the block copolymer polypropylene is (1.4~2.6):

1.

9. A method for preparing a polypropylene composite material, characterized in that, The preparation method is used to prepare the polypropylene composite material according to any one of claims 1 to 8; the preparation method includes: Polypropylene composite matrix, polypropylene grafted maleic anhydride and antioxidant are melt-blended and extruded and granulated under a first preset condition to obtain modified polypropylene particles. The modified polypropylene particles, carbon fibers, and fullerenes are melt-blended and extruded and granulated under a second preset condition to obtain the polypropylene composite material.

10. The method for preparing the polypropylene composite material according to claim 9, characterized in that, Before melt blending the modified polypropylene particles, carbon fibers, and fullerenes, the preparation method further includes: The carbon fibers and fullerenes were modified using a composite coupling agent to obtain modified carbon fibers and modified fullerenes, respectively. The mass fraction of the solute in the composite coupling agent is 0.2%~1.0%; the composite coupling agent includes γ-aminopropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane, and the weight ratio of γ-aminopropyltriethoxysilane to γ-glycidoxypropyltrimethoxysilane is (0.5~1.5):1.

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